Search for Life
in the Solar System and Beyond
Abstract
This visual story takes a general audience to appreciate the extraordinary fortune of finding life in the universe. For a more immersive experience, try reading in Morgan Freeman’s voice.
A world of extremes
To understand our Solar System can be quite challenging. For starters, our Solar System is huge. The Solar System is so big that kilometers are not very useful anymore. For the rest of our journey, we will be measuring distances with help of the speed of light (aprox 300.000 km/s)
If we try to compare planets, we have to observe multiple dimensions simulatenously. For example, temperatures, distances or densities that are unique on every planet. This would require different magnitudes that are incompatible with eachother (°C, Km, …).
These measurements are very different from planet to planet. If we tried to represent the planets with their real proportions, it would be impossible for your screen to show everything. For this, it is more useful to create “planet signatures”.
As you can see in Figure 2, signatures are unique for each planet and based on normalised data. This way we can compare dimensions like millions of kilograms and other extreme measurements, even if we have one huge planet compared to a tiny moon.
Earth, a dwarf planet
Earth is stricktly speaking, a dwarf-planet. Jupiter is more than twice as massive than the other planets of our solar system combined. (Laboratory 2023)
Mercury is still shrinking
Mercury is already the smallest planet in the solar system and it’s only getting smaller and denser. (Vicky Stein 2022)
Venus is too hot
Venus’ thick atmosphere traps heat creating a runaway greenhouse effect. (Vicky Stein 2022)
Every planet is unique on its own way. Planets can be made of rock, metal, gas,… each with different densities. We believe that over millions of years, the Sun has attracted the heaviest particles on its way. As a result, we find small, heavy planets near the Sun, while the less dense and gigantic can be found on the edges of the solar system.
Planets may also have moons, rings or asteroids belts. In some planets rain is water, while in other it rains diamonts or molten metal! But the most special and rarest of all possible outcomes, is life!
Life is so unlikely that it is almost considered accidental.
Earth is a comfortable place for life
The only planet known to contain life is Earth. Life is the result of many improbably coincidences. The most remarkable is its distance from the Sun. This makes possible to find water just at the right temperature for life to thrive.
Our neighbours Mars and Venus, are a few “minutes” too close or far from the Sun. Mars’ water is permanently frozen, while Venus is hotter than a steamer pot.
Water world
There is water everywhere in the universe. However, it has to be liquid to sustain life (Vicky Stein 2022)
Backward Stinky Sunrise
Venus rotates backward on its axis, opposite to most planets in our solar system. Its sulfuric atmosphere smells like rotten eggs! (Lunar and Institute 2023)
Organic molecules are everywhere
Organics are complex carbon-based molecules found in living things, but which can be created by non-biological processes too (Vicky Stein 2022)
Supersonic winds!
Winds on Neptune can blow up to 1,500 miles per hour (2,400 km/h). Is all that energy coming from the sun, from the planet’s core, or gravitational contraction? Researchers are working to find out. (Vicky Stein 2022)
There are many other factors to enable life, and each of them is required. A little bit too much radiation and you are fried. Decrease the gravity and the athmospere would disolve. Even the slightest change in the polarity of Earth’s core and a solar storm would put and end to life.
This makes us the luckiest tenants in the solar system. But, how about beyond the Solar System? The so-called “Exoplanets”, are they “Earth-like”?
Exploring the Vastness of our Universe: Exoplanets and their Discovery Methods
Our solar system is huge, as we have now seen. With today’s technologies we are able to get more Information about our solar system and get a better understanding. Companies like NASA or ESA have been studying our universe for years and have made considerable progress in the last decades. But what exactly is the universe?
The universe and it’s exoplanets
The universe is unimaginably big and nobody can say exactly how big it really is. But we know that the visible universe is about 93 billion light years in diameter. If you want to reach the star closest to the sun, it would still take 100,000 years to reach it at the speed of light (300,000 km per second).
The universe is a vast expanse, filled with billions of galaxies, each containing billions of stars. A large collection of stars and other celestial bodies form a galaxy. The galaxy we live in is called the Milky Way. Our exploration of the cosmos has revealed that many of these stars have their own planetary systems, known as exoplanets. Discovering and understanding these distant worlds is a fascinating endeavor that expands our knowledge of the universe and the possibilities of life beyond our own solar system. 1
Exoplanet Discovery Methods
Scientists have developed various methods to detect and study exoplanets. Three prominent methods with already many discoveries of exoplanets are Transit, Radial Velocity and Microlensing:
Transit Method: When an exoplanet passes in front of its host star from our point of view, it causes a slight dip in the star’s brightness. By monitoring these periodic brightness changes, scientists can infer the presence of an exoplanet and gather information about its size, orbit, and atmosphere. You can think of it like a solar eclipse, when the moon moves in front of the sun and blocks the light. More information: NASA: Ways to find a planet: Transit Method 2
Radial Velocity Method: This method relies on the wobbeling of the start, which is caused by the orbiting planets. By measuring these tiny periodic shifts in the star’s velocity, scientists can deduce the presence and characteristics of the exoplanet. More information: NASA: Ways to find a planet: Radial Velocity Method 2
Microlensing Method: In the vastness of space, massive objects like stars and planets have a profound impact on the fabric of space itself. This gravitational influence bends and redirects light, akin to a cosmic lens. These fascinating distortions unlock new perspectives for astronomers, offering a glimpse into the captivating mysteries of the universe. This temporary amplification provides valuable information about the exoplanet. More Information: NASA: Ways to find a planet: Microlensing2
These are the 3 main methods by which most exoplanets have been discovered over time. Other methods, such as imaging or transit timing variations, will not be discussed here.
In the visualization below, you can now see the number of exoplanets that have been discovered by each method. In addition, you can also view the top 10 most habitable exoplanets, how far away they are from earth in lightyears and with which method they were discovered. To do this, use the drop-down box and the checkbox, which you can select as you wish.
Data, tools and inspiration:
- Planets data (Banerjee 2022)
- Planets data 2 (Lunar and Institute 2003)
- Radar charts (Libraries 2022)
- Multiplots in plotly (RenaudLN, n.d.)
- Comparing Planet Volumes (polsci 2021)
- One level packed Circle (“Basic Circle Packing Chart” 2022)
| Planet | Volume | |
|---|---|---|
| 0 | Mercury | 6.083 |
| 1 | Venus | 92.843 |
| 2 | Earth | 108.321 |
| 3 | Mars | 16.312 |
| 4 | Jupiter | 143128.000 |
| 5 | Saturn | 82713.000 |
| 6 | Uranus | 6833.000 |
| 7 | Neptune | 6254.000 |
References
Banerjee, Sourav. 2022. “Planet Dataset.” https://www.kaggle.com/datasets/iamsouravbanerjee/planet-dataset.
“Basic Circle Packing Chart.” 2022. https://www.python-graph-gallery.com/circular-packing-1-level-hierarchy/.
Laboratory, NASAs Jet Propulsion. 2023. “Planets in Our Solar System.” NASA. https://solarsystem.nasa.gov/planets/overview/.
Libraries, Plotly Graphing. 2022. “Radar Charts in Python.” https://plotly.com/python/radar-chart/.
Lunar, and Planetary Institute. 2003. “Solar System Sizes.” NASA. https://solarsystem.nasa.gov/resources/686/solar-system-sizes.
———. 2023. “0 Need-to-Know Things about Venus.” NASA. https://solarsystem.nasa.gov/planets/venus/overview/.
polsci. 2021. “Packed Circle Graph with Circlify, Matplotlib and Plotly.” https://gist.github.com/polsci/d9ecd38934f690ded5cd6ca061359814.
RenaudLN. n.d. “How to Subplot Radar Charts with 2 Traces Each.” https://community.plotly.com/t/how-to-subplot-radar-charts-with-2-traces-each/64440/2.
Vicky Stein, Elizabeth Howell. 2022. “25 Weird and Wild Solar System Facts.” Future US Inc. https://www.space.com/35695-weirdest-solar-system-facts.html.